碳纤维复合材料新型皱褶夹芯结构制备及力学性能研究

The aim for structures with both lightweight and high performance is the eternal subject for the developing of aeronautics and astronautics all long. Foldcore sandwich structure which is a kind of lightweight core material in a vertical and horizontal zigzag folding patterns has great potential for the aerospace application. Traditional sandwich structures with V and M pattern foldcores are mostly folded by the thin aluminum foil and paper. The fiber direction will be suddenly changed at the corner of the folding ridges which are the germination point of failure damage if the foldcore structures are made by fiber composite materials. This project proposes typical innovative foldcore sandwich structures (S pattern) which are suitable for being fabricated by carbon fiber composite materials using hot press molding method. The bottleneck problem about the suddenly changed fiber direction at the corner ridge can be solved by the innovative foldcore architectures and then the load-to-weight ratio of overall structure will be improved. The content of this research can be divided in three main parts: the first aspect of work is the fabrication of carbon fiber composite innovative foldcore sandwich structures using hot press molding method with our own intellectual property rights in order to exploit the intrinsic strength of the fiber reinforced composites fully. The second aspect of work is to build the theoretical and numerical models for the mechanical properties of carbon fiber composite innovative foldcore sandwich structures, the failure mechanism maps will be conducted and then the experimental specimens will be designed according above models. The third aspect of work is the experimental analysis of carbon fiber composite innovative foldcore sandwich structures, including quasi-static and dynamic mechanical properties. The performance specification and the failure mechanism will be investigated. This project is aimed at laying the groundwork for the knowledge and valuable reference to the engineering application of carbon fiber composite foldcore sandwich structures.

轻质高强结构是航空航天发展的永恒主题，皱褶夹芯结构作为一种纵向和横向均呈之字形折叠的轻量化芯材结构在航空航天领域具有广泛的应用前景。传统的V型和M型皱褶夹芯结构多由薄的铝箔或纸折叠而成，若采用碳纤维复合材料予以成型，则在皱褶棱线拐角处存在纤维方向突变，易成为失效破坏萌发点。本项目提出多种适合碳纤维复合材料模压成型的新型皱褶结构(如S型)，解决棱线拐角处纤维突变的瓶颈问题，提高结构载荷质量效率。拟开展以下三个方面的工作：1) 充分发挥纤维增强的潜力，采用具有自主知识产权的模具热压法制备碳纤维新型皱褶夹芯结构。2) 建立预报碳纤维新型皱褶夹芯结构力学性能的理论与数值模型，绘制其失效机制图，并指导实验件设计。3) 对碳纤维新型褶皱夹芯结构进行静态及动态力学性能实验研究，评价结构的力学性能并揭示其失效机理。本项目研究可为人们对碳纤维皱褶夹芯结构的认识和未来该结构的实际工程应用奠定基础。

减轻结构重量，提高有效载荷是轻质结构不断发展的永恒主题，皱褶夹芯结构作为一种纵向和横向均呈之字形折叠的轻量化芯材结构在航空航天领域具有广泛的应用前景。皱褶夹芯结构是受折纸启发而来，传统的V型和M型皱褶夹芯结构多由薄的铝箔或纸折叠而成，若采用碳纤维复合材料予以成型，则在皱褶结构棱线拐角处存在纤维方向突变，在制备和承载过程中易成为失效破坏萌发点。本项目提出了一种适合碳纤维复合材料模压成型的曲面折纸皱褶结构(S型皱褶结构)，解决了棱线拐角处纤维突变的瓶颈问题，提高了结构载荷质量效率。开展了以下四个方面的工作：1) 提出了一种由V型皱褶结构向S型皱褶结构的转化规则，保证了简便易操作，并且不增加独立的几何参数，证明了S型皱褶结构的可折叠性和可展开性。2) 充分发挥纤维增强的潜力，采用具有自主知识产权的模具热压法成功制备了碳纤维S型皱褶夹芯结构。3) 建立了不同类型皱褶夹芯结构在几种常见载荷下力学性能的理论与数值预报模型，绘制了其失效机制图，并根据失效机制图设计了不同尺寸的试验件。4) 对碳纤维S型皱褶夹芯结构在几种常见载荷环境下进行了静态力学性能实验研究，评价了结构的力学性能并揭示其失效机理。理论分析、数值模拟以及面外压缩试验证明S型皱褶夹芯结构的抗屈曲能力要明显强于V型皱褶夹芯结构。本项目研究成果为人们对碳纤维皱褶夹芯结构的认识和未来该结构的实际工程应用奠定了基础。在固体力学或复合材料领域顶级期刊JMPS、CSTE等发表SCI学术论文7篇，基于项目部分研究成果，项目负责人入选中国科协青年托举人才工程和教育部青年长江学者。